| 1. |
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| 2. |
- Brena, Barbara, et al.
(author)
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Ultrafast Molecular Dissociation of Water in Ice
- 2004
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In: Physical Review Letters. - : The American Physical Society. - 1079-7114 .- 0031-9007. ; 93, s. 148302-148305
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Journal article (peer-reviewed)abstract
- Using x-ray emission and photoemission spectroscopies to measure the occupied valence levels in a thin crystalline ice film, we resolve the ionization-induced dissociation of water in ice on a femtosecond time scale. Isotope substitution confirms proton transfer during the core-hole lifetime in spite of the nonresonant excitation. Through ab initio molecular dynamics on the core-ionized state, the dissociation and spectrum evolution are followed at femtosecond intervals. The theoretical simulations confirm the experimental analysis and allow for a detailed study of the dissociative reaction path.
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| 3. |
- Janin, Emmanuelle, et al.
(author)
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Adsorption and bonding of propene and 2-butenal on Pt(111)
- 2001
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In: Surface Science. - 0039-6028 .- 1879-2758. ; 482, s. 83-89
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Journal article (peer-reviewed)abstract
- The adsorption of propene and 2-butenal on the Pt(1 1 1) surface has been studied by high resolution photoelectron spectroscopy, both in the mono-and multi-layer regime. The results obtained indicate an involvement of both aliphatic and carbonyl groups in the bonding of 2-butenal with the platinum surface in the sub-monolayer regime.
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| 4. |
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| 5. |
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| 6. |
- Nordlund, D., et al.
(author)
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Surface structure of thin ice Ih films
- 2004
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In: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 395:1-3, s. 161-165
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Journal article (peer-reviewed)abstract
- An angular dependent X-ray absorption spectroscopy study of the surface of thin ice films grown on Pt(1 1 1) is presented. Using different probing depths together with spectral calculations based on density functional theory, the spectra are interpreted in terms of the structure of surface, subsurface and bulk regions. It is shown that the crystalline ice is terminated with a large abundance of isotropically distributed free O–H groups and a distorted subsurface.
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| 7. |
- Ogasawara, H., et al.
(author)
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Structure and Bonding of Water on Pt(111)
- 2002
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In: Physical Review Letters. - : American Physical Society. - 1079-7114. ; 89:27, s. 276102-276105
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Journal article (peer-reviewed)abstract
- We address the adsorption of water on Pt(111) using x-ray absorption, x-ray emission, and x-ray photoelectron spectroscopy along with calculations in the framework of density functional theory. Using the direct relationship between the electronic structure and adsorbate geometry, we show that in the first layer all the molecules bind directly to the surface and to each other through the in-layer H bonds without dissociation, creating a nearly flat overlayer. The water molecules are adsorbed through alternating metal-oxygen (M-O) and metal-hydrogen (M-HO) bonds.
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| 8. |
- O'Shea, JN, et al.
(author)
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Hydrogen-bond induced surface core-level shift in pyridine carboxylic acids
- 2001
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In: SURFACE SCIENCE. - : ELSEVIER SCIENCE BV. - 0039-6028. ; 486:3, s. 157-166 Language: English
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Journal article (peer-reviewed)abstract
- Intermolecular hydrogen bonding in thick films of pyridine carboxylic acids (isonicotinic; picolinic and bi-isonicotinic acid) evaporated onto rutile TiO2(1 1 0) has been investigated with X-ray photoelectron spectroscopy and X-ray absorption spectroscopy
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| 9. |
- O'Shea, J. N., et al.
(author)
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Hydrogen-bond induced surface core-level shift in pyridine carboxylic acids
- 2001
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In: Surface Science. - 0039-6028 .- 1879-2758. ; 486:3, s. 157-166
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Journal article (peer-reviewed)abstract
- Intermolecular hydrogen bonding in thick films of pyridine carboxylic acids (isonicotinic; picolinic and bi-isonicotinic acid) evaporated onto rutile TiO2(1 1 0) has been investigated with X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. These molecules are shown to be strongly H-bonded in the condensed phase, and a surface core-level shift is observed due to the presence of non-H-bonded nitrogen atoms in the surface layer. Density functional theory calculations are used to relate the experimental data to the proposed bonding configurations based on the surface termination of the known equilibrium solid-state structure. A kinetic barrier, attributed to the high degree of molecular orientation required for the formation of extended H-bonding networks, has also been investigated.
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| 10. |
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| 11. |
- Schiessling, J, et al.
(author)
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Insulating surface layer on single crystal K3C60
- 2004
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In: European Physical Journal B. Condensed Matter and Complex Systems. - : Springer Science and Business Media LLC. - 1434-6028. ; 41:4, s. 435-438
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Journal article (peer-reviewed)abstract
- Using angle-dependent photoemission spectra of core and valence levels we show that metallic, single crystal K3C60 is terminated by an insulating or weakly-conducting surface layer. We attribute this to the effects of strong intermolecular correlations combined with the average surface charge state. Several controversies on the electronic structure are thereby resolved.
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| 12. |
- Wernet, Ph., et al.
(author)
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The Structure of the First Coordination Shell in Liquid Water
- 2004
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 304:5673, s. 995-999
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Journal article (peer-reviewed)abstract
- X-ray absorption spectroscopy and x-ray Raman scattering were used to probe the molecular arrangement in the first coordination shell of liquid water. The local structure is characterized by comparison with bulk and surface of ordinary hexagonal ice Ih and with calculated spectra. Most molecules in liquid water are in two hydrogen-bonded configurations with one strong donor and one strong acceptor hydrogen bond in contrast to the four hydrogen-bonded tetrahedral structure in ice. Upon heating from 25°C to 90°C, 5 to 10% of the molecules change from tetrahedral environments to two hydrogen-bonded configurations. Our findings are consistent with neutron and x-ray diffraction data, and combining the results sets a strong limit for possible local structure distributions in liquid water. Serious discrepancies with structures based on current molecular dynamics simulations are observed.
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| 13. |
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| 14. |
- Öström, Henrik, et al.
(author)
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Geometric structure and chemical bonding of acetylene adsorbed on Cu(110)
- 2004
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In: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 565:2-3, s. 206-222
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Journal article (peer-reviewed)abstract
- The chemical bonding and geometric structure of acetylene adsorbed on Cu(I 10) is analyzed using X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) in combination with density functional theory (DFT) total energy geometry optimizations and spectral calculations. XPS reveals two different adsorbed species at liquid nitrogen temperature. The molecular alignment is deduced from angle-resolved XAS, revealing that in one site the molecules are aligned with the C-C axis along the [0 0 1] direction and in the other site with an average angle of 35degrees to the Cu rows. The position of the shape resonance is used to deduce a C-C bond length of 1.35 Angstrom, which is close to the values obtained from the DFT geometry optimizations. XES reveals strong sigma-pi mixing and new occupied states close to the Fermi level, originating from the out-of-plane pi* orbital, which becomes occupied upon adsorption in agreement with the Dewar-Chatt-Duncanson model of the bonding.
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| 15. |
- Öström, H., et al.
(author)
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Orbital rehybridization in n-octane adsorbed on Cu(110)
- 2003
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In: Journal of Chemical Physics. - : American Institute of Physics. - 0021-9606. ; 118:8, s. 3782-3789
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Journal article (peer-reviewed)abstract
- We have investigated the local electronic structure of n-octane adsorbed on the Cu(110) surface using symmetry-resolved x-ray absorption spectroscopy (XAS) and x-ray emission spectroscopy (XES) in combination with density functional theory (DFT) spectrum calculations. We found new adsorption-induced states in the XE spectra, which we assign to interaction between the bonding CH orbitals and the metal surface. By performing a systematic investigation of the influence of different structural parameters on the XA and XE spectra, we conclude that the molecular geometry is significantly distorted relative to the gas-phase structure. The bonding to the surface leads to a strengthening of the carbon–carbon bonds and a weakening of the carbon–hydrogen bonds, consistent with a rehybridization of the carbons from sp3 to sp2.8. ©2003 American Institute of Physics.
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